DAVENPORT, Iowa (AP) — Jurors convicted an Iowa man Thursday of killing his pregnant wife after his third time on trial, rejecting his claims that an unknown intruder shot her while he was in the shower.

The jury found 23-year-old Seth Techel guilty of first-degree murder and nonconsensual termination of a human pregnancy. The former volunteer firefighter who once hoped for a long career in law enforcement now faces a mandatory sentence of life in prison without parole.

Prosecutors argued that Techel killed 23-year-old Lisa Techel on May 26, 2012, so that he could be with a co-worker with whom he had been exchanging sexual text messages for months and for whom he had promised to leave his wife. They said Techel shot his wife in their trailer in Agency, a tiny town in rural southeastern Iowa.

Lisa Techel, a county jail employee and reserve sheriff’s deputy, was 17 weeks pregnant with their first child.

Techel displayed no apparent emotion at the verdict, though his parents and grandfather hung their heads in the first row of the courtroom. Lisa Techel’s father, sheriff’s deputy Todd Caldwell, wiped away tears after all 12 jurors said they agreed with the guilty verdicts.

Techel is scheduled to be sentenced Sept. 15.

The texts between Techel and Rachel McFarland, who worked together at a job training center in Ottumwa, “read like a countdown to Lisa Techel’s death,” Prosecutor Andrew Prosser had told jurors. He said the messages in which Techel promised to leave his wife to be with McFarland the day before the slaying gave him a powerful motive to kill his high school sweetheart.

Techel had told police that he was in the shower that May morning when he heard a gunshot, came out and saw his wife wounded in their bed. He is heard on the audio of 911 calls sobbing as he says, “my wife’s been shot” and requests an ambulance.

His lawyers had argued that was the emotion of a man who witnessed his wife dying at the hands of an unknown intruder. Prosecutors suggested they were fake tears.

Jurors at two previous trials last year in Ottumwa and Mount Pleasant had been unable to reach a verdict. The third trial was moved to the Scott County Courthouse in Davenport, where relatives of the defendant and victim often packed the courtroom during the nine-day proceeding. Jurors this time deliberated about four hours over two days.